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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Posted on 14 September 2010 by gpwayne

This argument is part of a greater one that other planets are warming. If this is happening throughout the solar system, clearly it must be the sun causing the rise in temperatures – including here on Earth.

It is curious that the theory depends so much on sparse information – what we know about the climates on other planets and their history – yet its proponents resolutely ignore the most compelling evidence against the notion. Over the last fifty years, the sun’s output has decreased slightly: it is radiating less heat. We can measure the various activities of the sun pretty accurately from here on Earth, or from orbit above it, so it is hard to ignore the discrepancy between the facts and the sceptical argument that the sun is causing the rise in temperatures.

TSI from 1880 to 1978 from Solanki. TSI from 1979 to 2009 from PMOD.

But if the sun’s output has levelled off or even diminished, then what is causing other planets to warm up? Are they warming at all?

The planets and moons that are claimed to be warming total roughly eight out of dozens of large bodies in the solar system. Some, like Uranus, may be cooling. All the outer planets have vastly longer orbital periods than Earth, so any climate change on them may be seasonal. Saturn and its moons take 30 Earth years to orbit the Sun, so three decades of observations equates to only 1 Saturnian year. Uranus has an 84-year orbit and 98° axial tilt, so its seasons are extreme. Neptune has not yet completed a single orbit since its discovery in 1846.

This is a round-up of the planets said by sceptics to be experiencing climate change:

Jupiter: the notion that Jupiter is warming is actually based on predictions, since no warming has actually been observed. Climate models predict temperature increases along the equator and cooling at the poles. It is believed these changes will be catalysed by storms that merge into one super-storm, inhibiting the planet’s ability to mix heat. Sceptical arguments have ignored the fact this is not a phenomenon we have observed, and that the modelled forcing is storm and dust movements, not changes in solar radiation.

Mars: the notion that Mars is warming came from an unfortunate conflation of weather and climate. Based on two pictures taken 22 years apart, assumptions were made that have not proved to be reliable. There is currently no evidence to support claims that Mars is warming at all.

Neptune: observations of changes in luminosity on the surface of both Neptune and its largest moon, Triton, have been taken to indicate warming caused by increased solar activity. In fact, the brightening is due to the planet’s seasons changing, but very slowly. Summer is coming to Neptune’s southern hemisphere, bringing more sunlight, as it does every 164 years.

Pluto: the warming exhibited by Pluto is not really understood. Pluto’s seasons are the least understood of all: its existence has only been known for a third of its 248 -year orbit, and it has never been visited by a space probe. The ‘evidence’ for climate change consists of just two observations made in 1988 and 2002. That’s equivalent to observing the Earth’s weather for just three weeks out of the year. Various theories suggest its highly elliptical orbit may play a part, as could the large angle of its rotational axis. One recent paper suggests the length of Pluto’s orbit is a key factor, as with Neptune. Sunlight at Pluto is 900 times weaker than it is at the Earth.

Claims that solar system bodies are heating up due to increased solar activity are clearly wrong. The sun’s output has declined in recent decades. Only Pluto and Neptune are exhibiting increased brightness. Heating attributed to other solar bodies remains unproven.

Big Mystery: Jupiter loses a stripeIn a development that has transformed the appearance of the solar system's largest planet, one of Jupiter's two main cloud belts has completely disappeared. ... Known as the South Equatorial Belt (SEB), the brown cloudy band is twice as wide as Earth and more than twenty times as long. The loss of such an enormous "stripe" can be seen with ease halfway across the solar system. "

This appears to be a 'natural cycle':"The SEB fades at irregular intervals, most recently in 1973-75, 1989-90, 1993, 2007, 2010,"

If some of these years sound familiar, that's because they are La Nina years!

ansliss has hit the nail on the head: 'skeptics' using this argument are rejecting the sure evidence and accepting the extremely dubious.

It is bizarre to think that we can know the climate of the distant planets so well, and not know our own.

Such behavior is a very strong indicator that they are not interested in the truth in the first place. They are only interested in vaguely plausible arguments encouraging them to believe what they already believe; or worse yet, to hoodwink others into believing what they themselves know is false.

What is your source for this information? It has been known for years that there is some internal energy source, but that it is that big sounds doubtful. There is no fusion going on even at the core, after all.

At some point, could you explain why a 3-5C temperature change is the difference between glaciers and heatwaves?

I believe the data that the difference between ice ages is about 3-5C. I just don't understand. If the temperature outside is 3-5 hotter or colder, then I barely notice the difference. Unless the glacier happens to be on the edge of melting, then why does the small temperature change matter?

This is one of the arguments in my office that I am having trouble answering.

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Moderator Response: Good question, and the two responses are good, but please move to a more appropriate thread.

The reason why it makes a difference is because when you look at glacial growth and shrinkage, it's not a phase transition all by itself (crossing 0C, starting to melt the ice cube), but rather a change in relative rates.

Glaciers are constantly accumulating mass at the top - snowfall compacting into ice. Slight warming actually increases this rate, as it's more likely to snow around 0C than -20C; more water in the atmosphere for snowfalls.

This ice then moves down the glacial valley, driven by pressure from above, lubricated by meltwater at the bottom, limited by back-pressure from the ice at the lower end of the glacier.

At the end of the glacier (terminus) pieces constantly melt, break off (calving or splitting off large chunks). The rate at which this occurs depends on the air temperature at the lower end of the glacier and upon the water temperature.

If a glacier is 'static', or not growing or shrinking, then the accumulation and melt/break-off rates are identical. Warming increases the accumulation rate under many conditions (more snow, as above), but greatly increases the melt rate at the terminus. When the rates are out of balance, the total mass of the glacier changes - it shrinks under warming conditions.

This is accelerated by factors such as increasing calving and break-offs at the terminus of the glacier reducing the back pressure on the rest of the glacier - it starts to slide faster down the valleys, pushing more ice into the warm terminus. Increased meltwater along the course of the glacier has the same effect - speeding it's movement towards the terminus, the warmest area.

So - it's not a phase transition, but rather an adjustment of the accumulation/reduction rates of the glacier that affect its mass with temperature. Is that helpful?

mfripp - A simpler explanation, courtesy of somebody else here who I can't find a reference to at the moment.

A glacier isn't static - snow constantly falls at the top, turns into ice, moves down the glacier, and melts or breaks away at the bottom.

Think of this as a queue for concert tickets. The line is 100 people long, with 10 people a minute arriving, and 10 people a minute getting their tickets and entering the show. The makeup of the line is constantly changing, but stays at 100 people long.

Now change conditions - a few more (5 per minute?) people start to arrive for tickets, but another gatekeeper comes on shift and an additional 10 people per minute enter the show. That means every minute the line shrinks by 5 people, and after 20 minutes the line is gone.

It's not a phase transition, but a change in rates that previously balanced.

The distance from Jupiter's north pole to south pole is shorter than the distance from terminator to terminator (across the equator). This means that there is less intervening matter between the proposed heat source (the planet's core) and the cloud tops over the poles, then there is over the equator.

Jupiter's poles should be warmer then the equator, if the sun doesn't drive Jovian weather.

The author says "It is believed these changes will be catalysed by storms that merge into one super-storm, inhibiting the planet’s ability to mix heat."

Prior to the emergence of the second and third Great Red Spots on Jupiter, the planet's ability to mix heat was closely studied during the 1994 impact of comet Shoemaker Levi. There is virtually no mixing across the belts and bands of Jupiter for a super-storm to inhibit.
But there are these new super storms. These great storms are anti cyclones, high pressure areas of heat pushing up from the center, rather then low pressure storms like our hurricanes.
Think of them like the turkey timer that pops out when the bird is done.

It's not a matter of computer models. You can see Jupiter's "turkey timers" in a backyard telescope.
Unlike the stuff these guys are selling, Jupiter has global warming you can see.

@papertiger: Jupiter's internal heat source is not hot enough to completely override solar irradiation (the ratio of internal heat to solar irradiation is about 1.7, IIRC), but in any case the equator gets a lot more irradiation than the poles; both end up being pretty much the same temperature.

"There is virtually no mixing across the belts and bands of Jupiter for a super-storm to inhibit."

Perhaps not, but there is a heat exchange between the poles and the equator.

"Unlike the stuff these guys are selling"

Which guys are you talking about, exactly? Is this another snide comments suggesting pro-AGW scientists are charlatans?

In any case, you miss the central point: there is no observational basis confirming that Jupiter is heating up due to solar irradiance (which has been on a decreasing trend for the past decades).